Main types of locks include mortise, cylindrical, and rim. These designations are based on the design of the lock, how and where it engages, and how it is mounted to the door. Mortise locks are generally considered the heaviest duty products in the marketplace. They are typically used in area of high traffic or heavy commercial usage, where greater security is required. A mortise lock is installed in a mortised pocket in the door, with the housing of the lock contained in the door. The cylinder is screwed through the skin of the door directly into the metal lock case, with only the cylinder head and spin ring projecting from the face of the door. The lock case may contain a dead bolt as well as the normal dead latch for added strength and security. Cylindrical locks are a simpler design installed in two intersecting holes in the door. Normally a 2⅛″ hole through the face of the door intersects either a ⅞″ or 1″ diameter hole from the edge. The cylinder is contained in the outside knob or lever, away from the surface of the door. Rim locks are mounted to the inside surface of the door, with a cylinder installed on the outside surface in a hole bored through the door. They typically have either a spring latch or dead bolt operation, engaging a strike mounted to the frame around the door. There are several types of dead bolt mechanisms found on rim locks. Lock cylinders in these and all locks may be designed for standard keys readily available at local hardware stores or controlled access/high security keys, which are available only from the manufacturer and selected locksmiths.
Electrical and electrified products are typically electrically operated mechanical locks and include electromagnetic locks, alarmed or delayed exit devices, electric latch releases, auxiliary alarm locks, touch keys, card readers, keypads and other electrified means of activating or controlling a lock. In most cases, the outside lever is unlocked by a solenoid instead of a key, although a key can provide an override or safety feature. The main benefit of electronic access control is a more flexible and higher level of key control than the typical mechanical key system.
Commercial cylindrical and mortise locks may have several different functions to suit almost every combination of convenience and security requirements. The most common include passage, privacy, office, entry, classroom, and storeroom. Passage sets are not locks in the true sense of the word, but incorporate a lever or knob on either side of the door and a latch to hold the door shut. There is no provision for a key, as no lock cylinder is included. Privacy locks are the type used in a public restroom, or perhaps a residential bedroom or bathroom. They contain no cylinder and do not have a key. However, they can be locked from the inside for privacy, usually by a pushbutton built into the knob or lever. They generally include a provision for emergency access from the outside, often using a small screwdriver or pin to unlock the outside knob or lever through a hole in the trim. Hospital privacy latches have thumb turns on both sides so a nurse or attendant can gain entry to a patient's bathroom quickly in an emergency. Office locks are locked from the inside by a pushbutton. The outside lever or knob remains locked until unlocked with a key from the outside or by rotating the inside lever trim. The inside knob or lever is always free for immediate exit. Entrance or entry locks maybe locked by pushing and turning a button and are unlocked by key until the inside button is manually unlocked. They are also available with pushbutton locking, in which pushing the button locks the outside knob or lever until it is unlocked by key or by turning the inside knob or lever. The inside knob or lever is always free for immediate exit. Classroom locks (maintained) are always locked and unlocked from the outside by key. The inside knob or lever is always free for immediate exit. Storeroom locks (momentary) have a fixed outside knob or lever, and the latch is retracted by the key from the outside. The inside knob or lever is always free for immediate exit.
Locks are available in different grades, which relate to their construction and durability. These grades are a measure of application suitability. Most commercial applications require either Grade 1 or Grade 2 locking products. ANSI/NHMA standards, monitored by independent testing laboratories, separate Grade 1 from Grade 2. Typically, Grade 1 locks must meet twice the requirements of Grade 2. In cycle tests for example, a Grade 2 lock need only function for 400,000 cycles, while a Grade 1 lock must meet at least 800,000 cycles. Some manufacturers regularly test beyond that limit into the millions of cycles.
Typical products available as Grade 1 include cylindrical key and lever locks, mortise locks, heavy-duty mortise, auxiliary deadbolts, and the locks used with electronic or other access control hardware. For most high-traffic areas, such as schools, heavily used offices, stores or other public buildings, a Grade 1 mortise lock is preferred. Because its case is much larger than that of a cylindrical lock, it can be built to incorporate parts with thicker cross-sections and greater strength. An alternative would be a Grade 1 cylindrical key and lever lock, which is probably the most popular for retrofitting because little or no additional prep is required. For example, converting from a cylindrical knob set to a lever in order to meet ADA requirements usually entails drilling only two holes. To achieve higher security where heavy use or abuse is expected, combine the Grade 1 cylinder lock with an auxiliary deadbolt, providing this combination is allowed by the local building codes.
On a parallel note, electrically actuated overhead garage door opener assemblies have been in use for a relatively long period of time functional for automatically opening and closing garage doors through control by either an interior control switch or remote control means normally carried in the automobile making use of the garage. As discussed in U.S. Pat. No. 4,254,582, automatic garage door openers are commonly installed for opening and closing garage doors of the solid or single-piece assembly type wherein the garage door is pivotally mounted movable from closed position pivotally upwardly and rearwardly to an overhead, nearly horizontal position. With this type of garage door installation, two basic forms of automatic garage door opener assemblies are used, one of the friction engagement form and one of the rack and pinion form. With the friction engagement form, the electrically actuated garage door opener having an upper extremity of the door connected thereto travels rearwardly and forwardly along a nearly horizontal guide track with resilient rollers of the opener frictionally engaged with the guide track to supply the relative motion therebetween. In the rack and pinion form, the relative motion is supplied by a rotatable pinion of the opener moving along a rack of the guide track.